The invention relates to an observation device comprising an electronic display for providing additional information.
Efficient observation devices are used in particular for military and geodetic purposes. It is important that the devices be manageable, fast and easy to operate and as compact and light as possible. While it was previously usual to use a plurality of devices for different purposes, combined, multifunctional devices are preferably used today. This is advantageous from many points of view; for example, carrying a plurality of devices becomes superfluous and substantially faster change between the functions is permitted.
For example, in addition to the day observation function, such devices may have the following further functions: target plates for military applications or for hunting purposes, integrated rangefinders and direction indicators, an electronic display for providing additional information (in particular where a display image can be superposed with the day vision image), a night vision function, etc. Thus, it is possible, for example, to provide the user with an image of a camera, location information, for example in the form of a map, measured distances or directions, stored information regarding a sighted target object—such as, for example, susceptible points of an enemy tank—or temperature and weather information on the basis of the electronic display. In particular, these devices are often in the form of binoculars or field glasses having said special functions for respective specific intended uses.
For a device with both day vision and display image function, a design having two separate channels—a day vision channel and an information channel—is generally customary. The day vision channel is generally formed in the manner of a known telescope comprising objective and optically refractive and reflective elements. The information channel usually has an electronic indicator/display and a downstream display optical system. For example, a liquid crystal display (LCD), a display comprising organic or inorganic light emitting diodes (OLED or LED display), a relatively highly luminous high-contrast liquid crystal on silicon display (LCoS display), a digital micromirror display (DMD), etc. can be used as a display for this purpose. In particular, beam splitters are used for combining the day vision and the information channel or for superposing the day vision image with the display image. The resulting combined overall image can then be projected via an eyepiece into the eye of an observer.
For the use of such observation devices in the field, in particular a low energy consumption, a high level of compactness and a low weight of the device must be ensured. Thus, the maximum operating time of field glasses having a display function may be from a few hours to several days, depending on the battery or accumulator power provided.
In order to ensure a low energy consumption, in particular the use of energy-saving displays is advantageous.
However, a factor preventing the use of such energy-saving displays is that they also have a relatively low brightness and a relatively low contrast. Particularly when the display image is superposed with the day vision image, the additional information often cannot be clearly and distinctly recognized but—if at all—only with difficulty.
Various approaches have been known to date for solving this conflict of aims, namely combining additional information displayed as clearly and distinctly as possible with a day vision image and having as low an energy consumption as possible thereby.
For example, two different displays arranged side by side in the display channel can be used, one of the two producing a very bright image and the other a less bright image. Thus, for example, information in text form can be shown with the bright and high-contrast display—which however also has a high energy consumption—and on the other hand information which requires a relatively low contrast compared with the day vision image for clear recognizability can be inserted by means of the energy-saving display.
However, a disadvantage of this solution is the expensive and complicated installation of two different displays and that—in the case of display of information with the brighter display—a relatively large amount of energy is required, this in turn leading to a short duration of operation and/or requiring the use of large and heavy batteries or accumulators.